Infrared radiation homing missiles have been developed for tracking down aircraft or vehicles which utilize either gas turbines or other engines, as metal parts which are exposed to hot exhaust gases from the engines would tend to radiate infrared radiation. Thus, it becomes necessary, in order to decrease the vulnerability of aircraft, vehicles or other engine-driven equipment which have hot gas exhaust systems, to suppress the visible and infrared radiation.
One conventional method of suppressing the detection of infrared radiation is to have an elbow connected to the exhaust such that all parts which are exposed to the hot exhaust gases would be hidden from the view of an infrared radiation detector. However, arising with the use of the elbow are problems of hot exhaust gases recirculating within the cavity of the elbow, thereby aspirating atmospheric air into the cavity, and the inside concave surface of the same elbow being impinged directly by hot exhaust gases. As a consequence, this hot surface would emit infrared radiation, thereby defeating the purpose of the elbow. Also, the same surface would be overheated as it is very difficult to cool this upper surface--witnessed by the use of multilayered ducts to channel hot air away from the engine generator set--disclosed by Allard in U.S. Pat. No. 4,413,668.